Welcome to the Bunnings Workshop community @patelavnih. It's terrific to have you join us and many thanks for your question.
Do you think that the damage was caused by snails?
You might like to start by reading through some of these previous discussions on the topic: Ridding the garden of snails by @kaylah_rose and Use coffee grounds in the garden by @robchin. There's also an article which you could find helpful: Protect your garden from snails slugs and leaf eaters.
We have a whole range of products suitable for preventing snails in your garden if you'd like to check them out.
Let me mention @mich1972 as I'd like to hear her favourite methods of removing snails in her garden. I'd hazard a guess to say it might involve chickens though.
Please let me know if you need further assistance or have questions.
I will try suggested products from Bunnings .
yeap , that damage done by snail as I picked up big Snail from my Aloe plant.